Quantcast

Question Chroma Subsampling and Deep Color Calibration Help

logo98

Novice Member
I know next to nothing about all the details of how 4K works, so I'll try my best to explain my situation. I have a Panasonic Plasma (model G25) that I want to calibrate using the Spears & Munsil HD Benchmark 2nd Edition disk. My plasma has three HDMI ports, two of which I want to calibrate for games (Xbox 360 and Nintendo Switch) and the last port for 4K movies. I recently found out that 4K movies on a 1080p TV is supposed to look very good so the blu ray player I'm using is the Panasonic DMP-UB900 (not 9000). One of the things the calibration disk mentions is choosing a color space. I have no idea how these numbers are suppose to affect the picture, so out of the options available to me I decided to pick YBbCr (auto) and I popped in a 4k movie. The same with deep color, I picked auto (12bit priority) per its recommendation. Sure enough the playback info shows that the movie was indeed outputting in YCbCr4:4:4/ 12 bit so I'm assuming this is the optimal settings for color space and deep color that would be used for the calibration disk for my movie HDMI port? And for my video games HDMI ports, I'm again assuming that 4:2:2 and deep color off is the optimal setting since they are not 4K? These are the only two quirks of calibration that I'm having trouble understanding, and although the blu ray player gives me some recommendations, I still want to be absolutely sure that I'm using the proper settings.

One side note, the calibration disk I'm using is not a 4K Blu ray but a regular blu ray.
 

Attachments

Ormy

Member
I'm no expert in TV calibration but I have a few insights here.

First, you do not need to calibrate each HDMI port, the calibration is not tied to one HDMI port or another. The calibration settings you apply to the TV are tied to the picture mode you use (e.g. game/cinema/normal/dynamic/professional etc). So if you apply calibration settings while in 'cinema' mode and using HDMI port 1, all you need to do is make sure you're always in cinema mode and the settings will apply no matter which HDMI port you are using.

Also, many (usually older) TVs accept 4:4:4 happily but internally downsample to 4:2:2 or 4:2:0 without telling the user. Plasma displays were more known for this so check if yours actually displays 4:4:4, I very much doubt it will.
 
Last edited:

youngsyp

Distinguished Member
I know next to nothing about all the details of how 4K works, so I'll try my best to explain my situation. I have a Panasonic Plasma (model G25) that I want to calibrate using the Spears & Munsil HD Benchmark 2nd Edition disk. My plasma has three HDMI ports, two of which I want to calibrate for games (Xbox 360 and Nintendo Switch) and the last port for 4K movies. I recently found out that 4K movies on a 1080p TV is supposed to look very good so the blu ray player I'm using is the Panasonic DMP-UB900 (not 9000). One of the things the calibration disk mentions is choosing a color space. I have no idea how these numbers are suppose to affect the picture, so out of the options available to me I decided to pick YBbCr (auto) and I popped in a 4k movie. The same with deep color, I picked auto (12bit priority) per its recommendation. Sure enough the playback info shows that the movie was indeed outputting in YCbCr4:4:4/ 12 bit so I'm assuming this is the optimal settings for color space and deep color that would be used for the calibration disk for my movie HDMI port? And for my video games HDMI ports, I'm again assuming that 4:2:2 and deep color off is the optimal setting since they are not 4K? These are the only two quirks of calibration that I'm having trouble understanding, and although the blu ray player gives me some recommendations, I still want to be absolutely sure that I'm using the proper settings.

One side note, the calibration disk I'm using is not a 4K Blu ray but a regular blu ray.
All consumer video is stored in the disc as YCbCr 4:2:0, for space saving reasons. I'm not 100% sure this is the case for your Xbox 360 games but, I would assume so, seeing as the same space constraints exist.
Once the video is pulled off the disc you'll probably have the option to send it as YCbCr: 4:2:0, YCbCr 4:2:2 or YCbCr 4:4:4, with your Blu-ray player. LCD and OLED displays actually display the image in RGB and I'm assuming, again, that plasma does too. That being the case, to get from YCbCr 4:2:0 on the disc, to RGB on the screen, the video needs to be up-sampled through YCbCr 4:2:2 to YCbCr 4:4:4 then converted to RGB, to be displayed. Whether you choose your Blu-ray player or the TV to do this is largely up to you but, one may do a better job than the other with all this processing, or part of it. Panasonic Blu-ray player's have a very good reputation for processing chroma, so it's a pretty safe bet to let the player do the work up to the YCbCr 4:4:4 stage, as you have.
The 'deep colour' part is to do with colour depth or pixel depth. Blu-ray is stored as 8 bit video, as is all SD and HD video. UHD blu-ray is stored at 10 bit. Your display will be working at the 8 bit level. As such, with your Blu-ray and UHD Blu-ray content, you could argue you're adding a processing step that's not required, by using 12 bit out of the UB900. If it looks OK though, with no signs of artefacts, I'd let the player do it's thing here too.
I believe your Xbox 360 will be outputting RGB at 8 bit pixel depth.

From a calibration perspective, you're ultimately aiming to tune the whole video chain, from content to display. And you'd do this for each video format you're watching. So in your case, 1080p24 YCbCr 4:4:4 at 12 bit for Blu-ray. 1080p24 YCbCr 4:4:4 at 12 bit for UHD Blu-ray. 1080p30 RGB at 8 bit for Xbox 360 and whatever format the Switch is outputting.

The Blu-ray source will be easy to replicate as when you put in your Spears & Munsil disc, the video will be coming out of the player and displayed in the screen in exactly the same way as a Blu-ray movie, as that's what it is effectively.
Although you'll be calibrating for the same video format that's coming out the player, for UHD Blu-ray, the internal processing of the player to get 2160p24 HDR, YCbCr 4:2:0 at 10 bit to the 1080p24 YCbCr 4:4:4 at 12 bit, will be different to that of getting the Blu-ray video to what the player outputs. The starting place is different. You could argue that this is getting really anal now but, these are things you need to consider if you're after peak accuracy.
What you could do is buy the UHD Spears & Munsil disc for the task....

You could probably replicate the Xbox 360 and Switch video outputs by manipulating the UB900's video settings.

Ultimately, a dedicated test pattern generator is required for ultimate accuracy, so each of your sources video outputs can be replicated specifically...

I hope that all makes sense and that I'm didn't ramble too much. The most important point is that whatever you're using for a test pattern generator, how it gets to the TV should replicate how actual content from that source reaches the TV, in terms of video format.

Paul
 

logo98

Novice Member
My nintendo switch can only output at limited RGB and from the research I have done, I think full RGB is mostly useful for PC gaming while limited is better for TV gaming. Both my xbox 360 and blu ray player have options to output in RGB standard/ limited. So as far as the calibrations being done just for gaming, I should use the standard RGB color space at 8 bit (or deep color off) since it would add an additional step if using any YCbCr setting. Am I understanding that right?
 

youngsyp

Distinguished Member
My nintendo switch can only output at limited RGB and from the research I have done, I think full RGB is mostly useful for PC gaming while limited is better for TV gaming. Both my xbox 360 and blu ray player have options to output in RGB standard/ limited. So as far as the calibrations being done just for gaming, I should use the standard RGB color space at 8 bit (or deep color off) since it would add an additional step if using any YCbCr setting. Am I understanding that right?
Yes, exactly, if you can. Although, if the Xbox outputs full RGB (0-255) and the Switch only limited RGB (16-235), they need discreet calibrations.

You TV should be perfectly happy with full RGB, as long as it knows that's what it's expecting. I.e. it should be expecting video levels 0-255 and not 16-235.

Paul
 

Similar threads

Top Bottom